This problem is very straightforward, in a 2-D plane, Give you a polygen, you need calculate its area.
Input
One integer T indicates the number of test cases
Each case is started with one integer n which means the number of points of that polygen then n lines followed, each line is a pair of real number x y describe the x-coordinate and y-coordinate of point, points are descriped counter clockwise.
Output
One real number rounded up to 2 decimal indicates the area of polygen.